Improvement in separating gold from other metals



v 2Sheets--Sheet1 C. WIEGAN D.

Separating Gold frum other Metals. N0. 68,695.

Patented Oct. 11, 1875.

N. PETERS. PHOTO-LITMOGRAPHER, WASHINGTON. n O.

2 Sheets--Sheef2.

c. WIEGAND. Separating Gold from, other Metals. N0.l68,695.

Patented Oct. 11, I875.

Fig 5 Fig.8.

Inventor N. FEIERB, PNOTO-LITHOGRAPNER. WASHINGTON. D. C.

' UNITED "STATES- PATENT OFFICE.

CONRAD WIEGAND, OF VIRGINIA CITY, NEVADA.

IMPROVEMENT IN SEPARATING GOLD FROM OTHER METALS.

Specification forming part of Letters Patent N o. 1 68,695, datedOctober 11, 1875 application filed July 9, 1874.

To all whom it may concern Be it known that I, CONRAD WIEGAND, ofVirginia City, Storey county, Nevada, have invented an Improved. Methodof Refining Base Gold, or separating other metals therefrom, as also theapparatus adapted thereto. The following description will enable othersskilled in the art to which it most nearly apanother object in view,(the production of refined silver,) the removal of the silver from themixed amalgams, to the extent which is easily practicable by the saidmethod, constitutes -a helpful and important part of this gold-refiningprocess; for if not removed its presence would prove a seriousimpedimentto (if not frustration of) the later steps of the process, as ispractically found to be the case in the process patented as N 0. 48,438.Third, the production of a highly porous or spongiform state of the basemetals, throughout which the gold to be refined has been diffused byamalgamation. The object in ,view for obtaining the base metals in thisform is to fav vor their oxidation by roasting, ad apted appliances forwhich are hereinafter described and the aim of oxidation itself is toprepare the base metals for the next vital step. The production of onceamalgamated base metals in the spongiform state, and easily fitted forroasting, is attainable by retorting the silver-v denuded amalgam indescribed speciallyadapted retort-cups. Fourth, solution of thebase-metal oxides in dilute sulphuric acid, preferably after grinding orpulverizing the already roasted lumps of base metal, either with orwithout a preliminary additional roasting. Fifth, digestion of theresidue or sub: sidence of the dissolving-vats in hot, strong sulphuricacid, or in warm dilute nitric acid, or in warm dilute nitro-sulphuricacid, (or successively bytwowor more of these acids) for.

Second, the removal i the purpose of removing any portions of the basemetals which failed to dissolve in the original dilute sulphuric acid.vSixth, washing with water to dilute and remove adhering acid. Seventh,melting either with or without refining fluxes.

My invention consists in a process for refining metals, involving aseries of consecutive steps, and machinery for carrying them out, ashereinafter more fully described and claimed.

The silver separating apparatus consists, chiefly, of a heater,(furnished with a strainer,) a cooler, a collector, a mechanism adaptedto lifting quicksilver, a fume-condenser adjusted to the above apparatusfor precautionary purposes, and an inclined table or floor shedding to atank for receiving and saving any leakages or drippings of quicksilveror amalgam which may fall. The retorting, roasting, and dissolvingapparatus, besides furnaces, tanks, and vats com monly used, and,without description, Well understood by refiners and manufacturingchemists, embraces retort-cups of special construction, and originalstationary roasting boxes or pans,so contrived that heating themexternally in an ordinary cylindrical furnace, withoutany application ofmechanical power, causes an oxidizing circulation of air within them,while a reducing contact of fuel or flame with their contents isexcluded.

Figure 1, in diagram herewith, represents a general view of thesilver-separating apparatus and trap-floor, with their several partsconnected with oradjusted to each other.

Fig. 2 represents the supports and fastenings of the strainers in theheater and in a collector of similar construction. Figs. 3 and 4represent a sectional edge and top view of the spe cial I retort-cupsalready alluded to. Fig. 5 represents a sectional side view of acylindrical retort, (with condenser attached,) in which two tiers ofretort-cups are represented in position. Figs. 6 and 7 represent asectional side and top view of a roasting-furnace, with a tier ofstationary roastingboxes within. Fig.8 represents a sectional side viewof one of the special roasting-boxes already referred to. V

In Fig. 1, S F is an inclined table or floor,

which may either descend from two or more sides to acentral opening, 0 5or, if desired, it

, from the heater into the air.

an upright vessel whose sides are impervious to quicksilver, and,preferably,.made of iron.

mayinclineonly in one direction .to a side or edge. Beneath the openingO.(or beneath the be shed to the tank and saved.

H isthe heater, located at a height above the inclined table S Fsufficient to permit a cooler, G, andcollector K, or its describedsubstitute, and well W, being adjusted below and between it and theinclined table or sheddingfloor S F. From the collector K the coldstrained quicksilver is conducted into the well .ior tank W, whence itfeeds to a pump, or is scooped .up by the bucket of the elevator E,

.and is lifted to the quicksilver-reservoir Q B. ;Located,near the upperend of the heater H a pipe, q 10, connects this reservoir with the upperend of the heater, as shown. A U-shaped trap, u t, formspart of thispipe, and is designed to prevent mercurial fumes escaping The heater His It is surrounded with a heating-jacket, J J. The upper end of thisheater may be connected with a condenser,.M, by a condensing-pipe,c

1), through which any mercurial fumes generated in the heater can pass,and being condensed, when not conducted elsewhere, their escape into theair which operatives breathe is prevented.

The lower end of the heater may be enlarged ltogform a chamber of anydesired shape or Y size. Its enlargement increases the strainingsurfacewithout reducing the pressure; but

.all such enlargement may be dispensed with andspeed, attained byincreasing the height of the heater.

In Fig. 1 of the drawing a chamber is represented by flaring-the lowerend of the heater,

to which there is shown attached a funnel- 1 shaped bottom, f s I), (seeFigs. 1 and 2,) as

also a spout, 819, closed. with a gate, through .which spout thecontents of the heater may be removed without disturbing the strainer.

Between the funnel-shaped bottom and the lower end of the heater astrainer is secured by the two rubber rings 1' 0" being pressed againstthe edges of the strainer, one ring heing above and the other below it.The drilled plate et, in Fig. 2, is covered with wire-cloth, andsupports the middle of the strainer, while its own support is atheavierbed-plate, b pl, fitting in a cavity, 00, of the funnel-shaped bottom.The strainer itself may be made of punched iron or steel, (screen,) orof woven iron or steel .wire; orit may be hair-cloth,,duck, -muslin,skin,.or felt, and is to be, laid ontop of the above-described supports,sothat bolting the heater-flange to the flange of the funnel-shapedbottom will make aquicksilven tight joint, and compel the quicksilver topass throughthe strainer. A shortdependingpipe, P, furnishedwith astop-cock, s'c, connects the lower part of the heater with the cooler,and provision is also made by a small try-cock, t

c, forsampling the mercurial filtrate as it' strains from the heater.Though other forms for a cooler are admissible, that represented in Fig.l is a nearly horizontal pipe, T, surrounded by a cold-water jacket, Jil The lower end of this pipe opens over anddischarges into thecollector, which is simply a straining apparatus. That marked K in Fig.1 is a vessel furnished, like the heater, with a closed spout, 810, astrainer, s, and a funnel-shaped bottom, f s b. This strainer, however,may be made in any desirable form-for instance, in the form of a pair ofcanvas hose hanging from the-trough over necessary receiving-vessels,and supplied with stop cooks, which enable the operator to empty andcleanse one hoseof collected amalgam while the other is collecting more.A horizontal pipe, h '10, conveys the strained-out quicksilver from thecollector (or collecting-hose) to the tank or well W.

In Fig. 1 there is shown an endless band, bearing scoops or buckets. Theband passes over two pulleys. the scoops to dip into the well W.Theupper pulley empties the dipped-up quicksilver into the reservoir QB. Instead of this elevator an iron pump may be used for lifting thequicksilver, by attaching springs to the valves, designed to overcomethe levity of iron when immersed in quicksilver.

The form of retort is not important. In Fig. 5 it is represented. ascylindrical. The characteristic feature of the retort-cups which are Thelower pulley causes,

adapted toit is, that each cup is furnished with numerous parallelribs, 1) 1), Figs. 3 and 4, which mold the amalgam (while retortin g)into thin slabs or bars. The slabs can readily be broken into smallpieces without materially impairing the porousness of the retortedamalgam,

Fig. 6 represents a common upright furnace, with ordinary grate-bars.Onthese bars shallow roasting boxes ,or pans are set, in whose bottomsare apertures, through which air may rise from the ash-pit of thefurnace when the roasting'boxes are heated. The bottom of each box orpan is so formed as to serve the purpose of a cover to any similar boxon which it may be placed. The broken pieces of retorted amalgam beingput into these boxes, they are piled one on the other, and a grating orperforated lid is laid on thetop pan.

When a fire is built around the tier of pans or boxes, heat iscommunicated to the boxes and their contents, though fuel and flame arekept from reducing. contact with the base metals, and oxidation isaccomplished by the continuous circulation of air through the porousmass. An ordinary mill, (or battery furnished with a screen,) whichneeds no description, is sufficient to pulverize the roasted metalcold,,when.it is ready for acid treatment.

masts t Having thus sufficiently described my apparatus and utensils, itremains to show their use in carrying on the process herein set forth,and to claim in form whatI deem my invention, and entitled under the lawto protection in.

. merged in quicksilver.

The metals to be removed from the gold having been reduced with the goldto the form of an amalgam, the next step is to leach out, as far aspracticable, the silver which may be associated with gold. To do so,charge the heater (preferably through the feed-pipe f 19) with the baseamalgam, (dissolved to fluidity in quicksilver,) applying heat to theheater, and turning on cold water into the coolingjackets of thecondenser and cooler, while motion is imparted to the pump or elevator.To a great extent the silver is automatically leached out from the baseamalgam by the circulating heated quicksilver, and is caught in thecollector, leaving in the heater only an amalgam of base metals andgold. When steam or hot air is injected into the heater, either forheating or for agitation, care must be taken to keep the jet exceedinglysmall, as also to adjust an upper straining-cloth, s c 8, across the topof the heater, and below the mouth of the condensing-pipe 01), theintention of which is to prevent the quicksilver and amalgam beingcarried over mechanically into the condenser. The completion of theleaching is known by drawing off a sample of the filtrate as it strainsfrom the heater. After cooling and straining it, if the silver issufficiently leached out, only a trace of amalgam will be recovered fromthe sample. When the silver has been removed heat is to be withdrawn;but for the purpose of cooling the heater, besides other appliances, thepump or elevator may be continued in operation longer, after whichtheexcess of quicksilver having strained through-the gate of theheater-spout should be removed, and the amalgam taken out and retortedin the retort-cups, hereinbefore described, room being left in the cupsfor the swelling of the amalgam while retorting. The roasting of theretorted amalgam may be'done in an ordinary reverberatory furnace, as inthe Frieberg process; but it may be effected with less labor in anordinaryvertical furnace by the use of the roasting-boxes, hereinbeforedescribed. If the retorted metal, prior to roasting in theroasting-boxes, is broken into sufficiently small pieces withoutinjuring its porousness, and if the roasting heat is raised graduallyand protracted long enough, the greater portion of the base metals willbe oxidized and fitted for solution in weak sulphuric acid without asecond roasting after pulverization. If the roasted lumps are thenground or pulverized solution is. hastened, as is the case also when theacid is heated prior to introducingthe roasted metal. a A secondskillful roasting of the pulverized material will insure complete,prompt solution of thebasemetal oxides. The amount of acid employedshould be but slightly in excess of thechem ical requisite to formsulphates of the metals, andthe dilution should be butya little morethan is necessary for crystallization and warm aqueous solution. Furtherdilution (to prevent crystallization while subsidence of. the unoxidizedand insoluble portions is going on) can be provided for in specialsubsiding or settling vats, when there is not sufficient room in thedissolving-vat, or when time forbids its use for subsidence. The clearliquor having been drawn from the subsiding-vat, (aflexible siphon, thefeeding end of which is attached to a float, is a good device forthis'purpose,) the settlings may be digested in hot strong sulphuricacid, or, at a moderate heat, in dilute nitric or nitrosulphuric acid,orin two or more of these acids successively, in order to remove frommixture with the gold any soluble metal which may not have been fullytaken up by the dilute acid first employed; or, if it is in any placemore convenient to complete the process by a substitute for theselast-named humid steps, or to employ the process to an extent which willproduce only a partial refining of the gold, the subsidence may bemelted with the use of ordinary refining fluxes, and preferably in sandcrucibles; or it may be melted with simple cleansing fluxes in suchcrucibles as can be most conveniently obtained. But if the process, asalready indicated, is employed in its completeness after thefinal acidtreatment of the subsidence above named, the residue should be washed,and the gold produced will be found mintable, or, after melting andassaying, will be found salable.

I disclaim the process of oxidation by means of roasting-vesselsrevolving in a furnace or flame, to the interior of which vessels theair has access. I also disclaim the process of oxidizing. lumps ofretorted base amalgam by heating the same with access of air in boxes orpans generally.

Having thus described my process, utensils, and procedure, whatI claimas my invention, and desire to secure by Letters Patent, 1s-- 1. Theprocess herein described for refin' ing gold, consisting essentially ofthe following steps: First, the conversion of all amalgamable" metalsinto one amalgamated mass; second, removing the silver therefrom, as.hereinbefore specified; third, retorting the remainder, containing thegold, into a highly porous or spongiform mass; fourth, roasting the samewith access of air; fifth, dissolving the base-metal oxides in dilutesulphuric acid; sixth, digesting the residuum in hot strong sulphuricacid, or in dilute nitric acid, or in weak nitro-sulphuric acid;seventh, washing the remaining gold with water; eighth, meltmg. i

2. The heater H, constructed with the strainer, as described, and withsuitable supports for the same, substantially as set forth.

3. Thecollector K, constructed with adiaphragm, S, composed of theplate]; 12 Z, wirecloth 1? l, and cloth r, lying contiguous to eachother, substantially as and for the purpose set forth. 1

- 4. In combination with the silver separating and lifting apparatushereinbefore described,

the quicksilver-trap consisting of the shedding floor or table S F andtank A, as set forth.

5. In combination with the heater H and the condenser M, the strainer8-0 s, as herein described.

In witness whereof Ihereunto set my hand.

CONRAD WIEGAND.

Witnesses:

E. TERRA, J. WALDSTEIN.

